Fulfillment services do just that: they fulfill orders. This business mainly pertains to product order fulfillment, where a company receives the orders from their client, stores the products, packages them up and ships the items to the consumer. They act as sort of a middleman between client and end consumer, delivering on products and taking care of the merchant details. Services offered but a fulfillment center may include storage and warehousing, inventory control, pick and pack, and shipping. They may also handle returns and damaged merchandise, along with billing. Keep these popular fulfillment terms in mind before hiring a fulfillment services center or warehouse to distribute and store your products.

Pick and Pack – The process of choosing items in storage at the fulfillment services company, and prepping them to distribute and ship to the customer. Pickers are employees who work in the warehouse to find the item via the order manifest. They’ll take these items to the packer, who is an employee in charge of packaging up the order, making sure everything in the manifest is included. They attach a packing slip and ensure the shipping label bears the correct address.

Inventory – A list of items, such as goods, that are present in a store or building. This refers to a company's merchandise and raw materials that have yet to be sold.

Logistics – The coordination of a complex system of managing people, supplies, goods, or facilities. Those in charge of logistics are responsible for making sure operations run smoothly between people and places.

Telemarketing – The act of soliciting, selling, or promoting a product or service over the phone.

Warehousing – The process of storing merchandise in a central location to await shipping to the consumer.

A fulfillment service is a means of outsourcing the actual delivery of an order. Most of the businesses that use them are small direct mail or ecommerce stores.
A fulfillment service allows the client to focus on making sales and taking orders, while the service packs and ships goods. They generally distribute from a warehouse. The service handles inventory management and logistics, and is likely to also pick up or receive returns.
While the service distributes, warehouses and ships, the retail business markets and bills. Without having to worry about storage and supply, the merchant can focus on selling.
A fulfillment service may also operate a call center and handle telemarketing for clients. Such a call center may be outsourced overseas. The warehouse handles packing, delivery and when necessary pick ups. Some fulfillment centers may handle their own shipping, others may utilize a package delivery or courier service.
Fulfillment services are particularly important in the book publishing industry, where they may collect books from the printer and ship to stores. Due to the large number of returns, most of the logistics are handled by fulfillment services or book distributors. Such services also handle magazine subscriptions. Other fulfillment specialties may include clothing and vitamin supplements. It is common, also, for a fulfillment service to handle the printing and mailing of catalogs, although the importance of the traditional catalog has been reduced by the internet. Some services also handle television and radio advertising, or web site design.
For the most part, fulfillment services work with very small companies and vendors, or inventors who are unsure how to get a product to market.